Pasta sauce is perhaps the quintessential “How long will it keep?” product. If you’re cooking for a small household—1-3 diners—you’re not likely to polish off a large jar at one meal, and it’s hard to find a small jar on store shelves. Therefore, you may regularly find yourself left with half a jar. But how soon are you going to want pasta again? You put the remainder in your fridge, and, before you know it, ten days have passed. Now what? Is it still good? Would it be obvious if it weren't? Can pasta sauce turn dangerous? Probably not, you think. On the other hand, it probably won’t taste too good anymore, so maybe it should be tossed. But, then again, it would be a pity to waste a half jar. And round and round you go.

Stop spinning. Our Advisory Board scientists have provided guidance, and manufacturers’ websites and customer service phone staff offer additional information. Not everyone has exactly the same answers, but you’ll get the general message that this is not a product to save for months.

ADVICE FROM OUR ADVISORY BOARD SCIENTISTS

From food scientist Dr. Catherine Cutter: “Keep in mind that “use-by” dates on unopened jars are about quality, not safety. Once the lid is off, other factors come into play. For example, lactic acid bacteria (LAB), yeast, and mold are the primary spoilage organisms of tomato-based products. Of these, mold would be the biggest issue in that some types of mold can produce mycotoxins. Therefore, open product should be discarded when it looks, smells, or tastes bad.

The length of time a sauce can last once it’s open depends upon how well the product is treated and the storage temperature. Was a clean spoon used to remove the sauce? Was the jar left open for an extended period of time on the counter before putting it into the refrigerator? The more opportunities that LAB, yeast and mold have to contaminate an open jar, the sooner the product will spoil. Finally, the temperature in the refrigerator can affect shelf life. Refrigeration of less than 40°F, slows down microbial growth and may be able to extend the shelf life of the product a day or so. On the other hand, a refrigerator cooling only to 45-48°F will speed up microbial growth.

Assuming careful handling, left-over tomato-based pasta sauce that has never left the jar should remain good (both safe and tasty) for 1- 2 weeks. (Food scientist Dr. Joe Regenstein goes as high as 14 days, as does at least one manufacturer.) Most tomato sauces have a high acid content, which restricts microbial growth and gives the product stability.

Leftover pasta sauce that has already been heated should be kept for a maximum of 3 days (the usual length of time that consumers are advised to keep leftovers). Some food safety experts advise consumers not to reheat leftovers more than once because products that have been heated, refrigerated, and then reheated have twice gone through the “danger zone” (temperatures between 40°F-140°F), the temperature range in which bacteria multiply rapidly. However, Dr. Regenstein points this out: “It is a time/temperature relationship. If you heat the product quickly, a second reheating should not be a problem—especially if the final heating is hot enough to kill pathogens. Obviously, if there is an off-odor or off-flavor, thee product should not be used.”

From Dr. Cutter: “Dairy can reduce the length of the shelf life, but it depends upon the type of dairy. Hard cheeses (such as romano or parmesan,) have low water activity due to their drying and salt, so the addition of these cheeses to the sauce may not impact the shelf life much. However, the addition of a cheese/alfredo sauce can neutralize the tomato sauce (increase the pH to near neutrality). In that case, it should be eaten pretty quickly after opening.”

According to food scientist Dr. Karin Allen: “Leftover alfredo sauce should be eaten or discarded within 4-5 days.”

Meat, mushrooms, and olives added to commercial pasta sauce are not an issue,” Dr. Allen assured us. “The pasta has already been canned, so it’s just as stable as a plain pasta sauce.”

AND NOW A WORD FROM PASTA SAUCE MANUFACTURERS

Labeling

The labeling on the jars ranges from some to no help in answering the question of the open jar. Those that do go to the trouble of addressing the issue provide a wide range of answers and suggestions. Culinary Circle urges use within 3 days of opening. The generic Albertson's brand pushes it to 5 days. Barilla and Classico advise that it is “Best if used within 5 days.” And at the far end of the spectrum, Prego allows a whopping 14 days of refrigerated storage--at least the jar does. The website is mum on the subject.

How long will it last in the freezer?

Among the various brands' websites, there is nearly unanimous agreement that pasta sauce can be frozen for three months, so this is your best course of action if you only occasionally get bitten by the pasta bug. Both Ragu and its sister brand Bertolli, however, do NOT recommend freezing its cheese-based sauces, so if you're considering buying a jar of that, know that this involves genuine commitment to it. Ditto the Francesco Rinaldi brand alfredo and vodka sauces. Pasta sauce left in the freezer longer than 3 months may suffer a decrease in quality, but it will still be safe to eat since pathogens cannot grow at freezer temperatures.

Manufacturers’ Websites on Open, Refrigerated Sauce

The website FAQ's of most brands address the issue of the open jar almost immediately, with the exception of Prego's, which was no help at all on practically anything, but it does link you to some delightful recipes at Campbell's Kitchen. Others--Classico, Barilla,Ragu,Newman's Own—answer the questions, and there's not a lot of daylight between them. Classico and Barilla both give a 3-5 day range. Ragu and Newman's Own stretch it to 7 days, with the latter adding this disclaimer: “They may keep longer but are susceptible to spoilage.” The aforementioned Francesco Rinaldi puts the maximum for best quality at 5 days, adding, “It is worth noting however, that this length of time can vary quite a bit based on a variety of factors including the temperature of your refrigerator and how long it sits out while being used.”

What Customer Service Told Us

The customer service rep and website FAQ for a particular brand do not always agree. Perhaps it's that live, personal communication inspires one to be more cautious about advice, but, for example, while Bertolli's website gives pasta a liberal 10 days, the woman on the phone very strictly made it 3-5 days, reminding me that the Bertolli sauce has NO PRESERVATIVES.

Over at Ragu, the recorded message flatly stated a 3-5 day range, a bit less than the “up to 7 days” allowed by the company’s FAQ. Prego gave the open jar a comfortable 7-10 day zone, which, significantly reduces the jar's message of a 14-day allowance.

OUR FINAL PIECE OF ADVICE

If you aren't in the mood for another pasta meal but just want that darn open jar of sauce out of the way, there are plenty of other uses for it. We haven't yet found a dessert recipe that sounds quite appealing enough to recommend (feel free to offer). Meantime, these suggestions are pretty solid. Bon appetit!